1. Field of the Invention
The present invention relates to the field of drilling teeth to remove decayed enamel or other tooth matter and provide a surface of the proper size and shape to receive a dental restorative filling. More specifically, the present invention relates to a method and apparatus for drilling teeth with one or more high-pressure water streams with or without abrasive materials suspended in the water.
2. Technical Background
According to the American Dental Association survey center, in 1990 alone, there was an estimated 151,810,000 dental filling procedures performed in the United States. Currently the most widespread and notorious method for removing tooth matter in a cavity filling procedure is through a high speed drilling process. Drilling is often associated with substantial discomfort and anxiety. Most people find going to the dentist and having a cavity filled a very unpleasant and painful experience. Some people even develop phobias of visiting the dentist from the accompanying sounds, smells, and pains present in a typical drilling process.
A high speed dental drill is a mechanical drill that is driven by an electrical or pneumatic power source with a bit at the end. The drill bit is designed to remove small pieces of tooth as its rotating head contacts a tooth. This removal method functions much in the same manner as does an industrial drill when removing portions of metals or ceramics. A dental drill is typically handheld and easy to position in most areas of the mouth for removing tooth decay. The drilling process often requires water to cool the tooth being drilled and a vacuum to remove the water and tooth debris. The drilling process has the advantage of being low cost and well accepted in the dental field. Nonetheless, drilling does have many disadvantages in dental applications. cutting action of the rotating bit may damage the enamel, which may weaken the structure of the tooth. The process is intrusive for the patient and the size of the drill bit often requires the removal of considerable more healthy material than would otherwise be necessary.
The patient often experiences discomfort from the grinding and vibrations in the vicinity of tooth nerves that may already be stressed due to decay of enamel. During this process, the patient hears the constant, high-pitched whine of the drill motor, which is associated with pain and discomfort by many people, and may be downright frightening for others. To compensate for the pain and discomfort of a drilling procedure, large amounts of pain reducer may be required which can lengthen the process as a result of the necessity of waiting for the medicine to take effect. The use of medication also increases the cost of the procedure. The result of these problems is that the process of drilling a tooth entails several minutes, or even hours, of discomfort and anxiety for the patient.
Alternative methods of removing decaying tooth matter have been investigated to overcome the shortcomings of dental drilling. One such method is air abrasion. Air abrasion units use pressurized air to propel and direct small abrasive particles onto the tooth resulting in an abrading away of the surface. An abrasion units are used quite effectively for shallow, surface cavities and tend to conserve more of the healthy tooth than the high speed drill. Also, because the impact of the abrasive particles on the tooth are so minute, vibrations are insignificant and usually pain relief injections are not required. This saves time and also increases comfort to the patient. However, the air abrasion method is not as time effective when it comes to drilling below the outer enamel layer of the tooth and into softer tissues. This is due, in part, because the softer tissue just beneath the enamel surface, called dentin, partially absorbs the impact of the abrasive particles. The particles tend to bounce off this portion of the tooth, diminishing the excavating effects of the abrasive stream.
Another alternative to drilling that has been introduced recently is laser drilling and cutting technology. Lasers are the most precise method of removing tooth matter in the dental industry. They are capable of penetrating the tooth surface and underlying tissues in a highly controlled fashion and with the smallest width of cut of all of the presently available methods. Although the use of lasers does produce a heat-affected zone on areas of the tooth adjacent to the cut, several studies have shown that these effects are not significant enough to cause permanent damage to the health of the tooth. Although the laser offers significant benefit in dental applications, very few dentists use them. This is primarily due to the fact that they cost significantly more than alternative methods. Also, most dentists are not yet ready to invest in a technology without knowing that it provides significant improvements over their current method.
In developing a new decay removal method there is a need for an apparatus and method capable of removing decayed tooth material that is better suited to preserve a maximum amount of healthy tooth material. Leaving as much healthy tooth matter in place as possible helps to maintain the overall strength of the tooth and minimize the chances of cracking the tooth later on. In the case of the high speed drill, the minimum cutting dimension is limited by the width of the cutting tool. Relatively large amounts of healthy tooth material have to be removed in order to sufficiently reach the decayed portions. The air abrasion and laser methods have the ability to make smaller cuts and are thus able to conserve much more of the healthy tooth than had previously been possible. But, with the more precise cutting abilities also comes a limitation in the speed of the process, type of material that can be removed, and the cost of the equipment required. Because these methods are able to remove only relatively tiny sections of a tooth at a time, they also require more time to remove larger sections of material.
Consequently, there is a need for an improved apparatus and method for drilling teeth. The method should be effective for rapidly removing enamel and other decayed material with a minimum of discomfort for the patient. Thus, the apparatus should preferably operate quietly and with a minimum of appliance that must be simultaneously inserted into the patient's mouth. Furthermore, the apparatus should operate inexpensively, and function with equipment easily integrated with current dental office systems. Such a device should be self-cooling and accurate, so that healthy tooth structure is preserved. Moreover, such a method should minimize pain to the patient and should not be psychologically stressful for the patient, for whom the prospect of going to the dentist is already distressing enough.